QoS: InfiniBand Service Level (SL)
Applications may need to differentiate one data stream from another on a per QP basis.
This is accomplished by mapping an application QoS to an InfiniBand SL.
- Application mapping is outside the InfiniBand specification scope.
- SLs are interpreted on a per subnet basis.
- SLs are transmitted end-to-end within a subnet.
- SLs are transmitted within the Local Route Header (LRH).
- Switches and Routers contain a SL-to-VL mapping table.
- For multi-subnet, QoS is communicated via Tclass in the Global Route Header (GRH).
- A TClass to SL interpretation will be defined in the future.
Questions for IP over IB:
- What mapping function should be used to map IP DiffServ to IB SL?
- What mechanisms should be defined to provide bandwidth management?
- What mechanisms should be defined to identified flows across subnets, i.e. fill in the flow-label within the InfiniBand GRH?